Decoding Sherlock
by BubbleXGumXPink
Summary: It's been two years since the Reichenbach Fall and life in 221B Baker Street is back to normal now that Sherlock has returned. But normal has an entirely different meaning when applied to the unlikely flatmates and this time it involves their new neighbour and a new case to crack. Sherlock/oc.
1. Chapter 1

First Deductions

**Hey there! This is my first attempt at a Sherlock fic so apologies if anyone (particularly Sherlock seems a bit ooc. This does involve Sherlock/oc so if it it's not your cup of tea don't complain to me!**

**Enjoy! **

It was close to 8 o'clock in the morning and John was sitting in his favourite chair, newspaper folded on his lap and sipping a cup of tea. Sherlock on the other hand was lying across the whole sofa with his long legs dangling over the other end and his eyes closed. His hands, as usual, had adopted a steeple shape, middle fingers just touching his chin.

They sat like this for the next few minutes until they heard a small knock at the door and Mrs Hudson calling up the stairs 'Don't worry I'll get it!' Not that Sherlock was planning to get up anyway. John on the other hand looked up and then across at Sherlock to check of he was still breathing: twice now he had gone to his 'mind palace' only to have stopped breathing for several seconds. John made to stand up when Sherlock turned his head slightly and spoke.

'Don't bother, if Mrs Hudson's been talking this long it won't be long before she brings them up.' His voice was monotone and completely devoid of any emotion. To make matters worse he was right for a minute later they heard footsteps on the stairs, though oddly only one pair.

Sherlock sat up, no doubt hoping it was someone with a new case, and turned to look at the doorway where a young woman appeared. She was of medium height with long blond hair trailing down her back and a full fringe. She had green eyes and despite her apparent tiredness (bags under her eyes, the stifled yawn, john was almost proud of his deduction) she was quite pretty. She stepped forward into the room and gave small smile.

'Hi,' she started, 'I'm Samantha, or Sam for short, I've just moved in next door and thought I'd come and introduce myself.'

Sherlock stood up and walked towards her, studying her up and down. John sighed; he knew what came next and knew it would be harsher than normal now Sherlock knew she wasn't here with a case.

'Hmmm, five foot six, thirty, naturally brunette, recently moved from Portsmouth, no boyfriend, wearing the same t-shirt as yesterday: the crease is a giveaway. Not had much sleep, possible family problems from the way you're clutching your phone in your pocket. Either that or waiting for an answer to a job interview but unlikely if you've just moved.' He smirked at her dumbstruck face and was about to walk away when a fist collided with his nose, a loud crack filled the room as he fell backwards.

'That, Sherlock Holmes, is for being an arse. Yes I'm wearing the same t-shirt as yesterday because I moved here last night and everything's still in boxes. Yes I'm currently dealing with family issues: my mum's in hospital with cancer at this very moment and happens to be the very reason I moved back here. I can tell by the way Dr Watson is finding great amusement in your situation that you do this often to people. The mark on the underside of your chin also tells me you're the idiot who plays the violin at one o' clock in the morning and therefore the reason I was awake most of last night.'

Mrs Hudson chose that moment to appear at the top of the stairs with a tray of mugs and biscuits. She gave a slight squeal and almost dropped the tray when she caught sight of Sherlock sitting on the floor clutching his wonky nose that was dripping blood.

'Sherlock! You're getting blood on the carpet! Someone get him a tissue!' the landlady scolded, not bothered that yet again Sherlock Holmes had blood on his face. John took that as a cue to grab a box of tissues off the desk and hand it to Sherlock before holding his hand out to this woman who had dared to hit Sherlock.

'Glad to meet you Samantha, nice punch by the way it is something he deserves quite often.' He joked as she took his hand.

'Please, call me Sam and trust me it felt good after his bloody violin kept me up last night.' She grinned back, green eyes sparkling with mischief.

'Well then _Sam_ please have a seat.' John gestured to the armchair he had just sat in; sacrificing it so that she wouldn't have to sit next to a sour faced Sherlock. Mrs Hudson set the tray on the table and passed mugs to Sam, John and Sherlock. She stood there with hands clasped in front of her watching them.

'Anything else before I go?' she asked looking between the three.

'No, thank you Mrs Hudson.' John smiles and she bustles off back down the stairs to her own flat. They sit in silence for a few seconds, unsure where to start until Sherlock finally speaks.

'How did you know our names?' he asks in a tone that suggests he has guessed the answer already and only asks for Johns benefit. John himself was only just realising that she had seemed to know their names.

'Easy, I'm far-sighted and read the names off of the letters on the desk. As for who was who it was a combination of a guess and that Dr Watson had a more caring look.' Sherlock gave no sign of acknowledgement except to lean back into the sofa. John raised an eyebrow, several thoughts running through his mind including _Jesus Christ she's just like him but with more…emotion_ and _well at least she's dressed unlike Miss Adler._

'So, what do you do? As a job that is? And if we're to call you Sam then you can call me John, Sherlock on the other hand you can call whatever you fancy.' At this he got a rather reproachful look from his roommate.

'I'm a crypt-' Her answer was cut short by a small blast of police sirens directly below the window and flashing red and blue lights. Suddenly Sherlock was alert, bloodied nose forgotten as they heard the door open and slam shut. A man with short greying hair came running up the stairs, taking two at a time.

'Sherlock, we've got a case. Strange one; random woman poisoned and the guilty party left a clue.' The man plunges straight in, not even noticing Sam.

'A clue? Why do you want me if there's a clu- ah no it's not just any clue is it, it's a… code?' Sherlock deduces quickly enough and the man nods.

'Excuse me, did you just say code?' Sam pipes up; standing to make her presence known to the stranger who she guessed was some sort of detective. He looks her up and down before holding his hand out.

'Detective Inspector Lestrade, and who might you be?'

'Samantha Tate and codes are somewhat a speciality for me.'


	2. Chapter 2

A/N: Hey there! here's the second chapter, and as you've realised im a slow updater but please do keep with me :D also i forgot but i do not own anything except my oc Samantha.  
hope you enjoy :)

* * *

Ten minutes after Lestrades intrusion Sam found herself rather unamusedly squashed between an indifferent Sherlock and an uncomfortable looking John. They were in the back of a Taxi on the way to Scotland Yard after Sherlock refused to travel in Lestrades police car. Silently they watched London flash past.

The taxi pulled to a stop outside an old house, the window frames peeling and the door a discoloured white. People in white suits were moving in and out of the building and Sam assumed they were forensics. A tall man with neatly parted hair and a large nose stood next to Lestrade as Sherlock stepped out of the taxi, leaving John to pay.

'Anderson, what are you doing here?' Sherlock sneers with an unmistakeable look of hatred.

'I could ask you the same.' The man replies in a nasal sounding voice, 'and who the heck is she? Roped in another one?' he continues when Sam walks towards Lestrade.

'Oh I'm sorry, I didn't realise my name was 'she' please find some manners and next time do your research.' She saunters on into the house followed by John and Lestrade who disguise their laughter by coughing. Sherlock glares at Anderson before turning on his heels and sweeping through the door.

Lestrade, Sam and John were half-way up the stairs when John spoke. 'You do realise, Sam that you just repeated the same words to Anderson that Sherlock said to him on my first case?'

Sam looked at him curiously, 'how so?'

'You told him to 'do your research.'' John replied with a smirk, 'the plank called Sherlock a psychopath.'

'Oh,' nodded Sam, 'I pegged him as more of a sociopath.' At this comment John stopped in his tracks and turned to look at her.

'Are you a mind reader or something?' John asked as Sherlock caught up.

'Don't be absurd John,' the dark haired detective said, 'No one can read minds, only their actions and appearance.'

They continued on through into a small kitchen with a wooden table and chair. It was at this table that the victim was sat. The victim was a young woman; her body slumped over the table, blonde hair spilling out around her head. Her head was turned on its side, blank eyes stared into nothing.

Sherlock snaps on a pair of latex gloves as John hands Sam a pair and begins investigating. Whilst the two men investigate the women Sam heads over to Lestrade who is leaning against one of the kitchen counters; watching Sherlock and john.

'So what's the deal with these two? Couple? And surely they're not professional either?' she asks out of curiosity. For some reason the name Sherlock Holmes was ringing a bell but she couldn't grasp why.

'No on both accounts. Whilst they both act like it John has a girlfriend and Sherlock insists he's 'married to his work' why are you interested anyway?' Lestrade told her as they watched Sherlock and John survey the room and the woman's body

'Because I'm their new neighbour and would rather I didn't say anything stupid. I thought you had a code for me to crack anyway?' Sam replied eventually, looking expectantly at the DI. He nodded and handed her an opened envelope. She takes out a pair of simple black rimmed glasses and puts them on. On the front, written in a neat scrawl, was the phrase 'catch me if you can…' in blue ink. Carefully she opens the seal and pulls out the piece of paper inside. On the paper, in the same blue writing, was a mess of what appeared to be random letters.

'Xifs qfpqmf tmffq tjmfou boe tujmm cvu ofwfs xblf  
vgdqd zmfdkk rszmc khjd rsnd rdmshmdkr sgzs hm sgd czqj lzjd xnt ptzjd'

Samantha stared at the odd combination of letters for a few seconds, turning it this way and that in the dim kitchen light. Frowning she held it up against a small window in the corner in hope it might reveal some hidden clue.

'Any ideas?'

'Well I was hoping there might be some sort of clue on this paper but no. The only thing I can do is try out the types of codes I know. I can automatically rule out any codes that involve symbols but it does appear to be some form of substitution. Do you have a pen and some paper?' Sam concludes as she turns to look at Lestrade. He raises an eyebrow at her evaluation of what to him was a nonsensical grouping of letters and begins fishing around in his pockets. Finally he pulls out a black biro and a small notebook.

'Here use this.' He hands them to her and turns to Sherlock and John who were heading over to them. 'What did you find?'

'She's about twenty year old, student, welsh. Was suffering from homesickness and had mild depression. She has a roommate and a boyfriend, both of whom need questioning.' Sherlock reeled out the list of deductions without a second thought. Lestrade nodded and left to make the necessary phone calls.

Sam began scribbling out notes, ciphers and keys into the notebook and slowly began working through her memory bank of codes starting with the simplest. A second later her pen paused and she looked up at Sherlock.

'What did you say was the cause of death again?' she asked wondering if it was even mentioned.

'Ah, now it seems the forensics here and the police believed that it was poison, pots of food and samples of her drink all accompanied with some tester sticks, all of which are negative. So the cause is not poison. There is no sign of a weapon used and nothing to suggest she was attacked. The colour of her face however denotes possible choking. She was not strangled as there are no marks or bruises about the neck that leaves her having swallowed something, but how? How did she not notice the object that would cause her death? Now we could say perhaps it was a bone, an accident but then why would there be a note addressed 'catch me if you can'? So it's a murder and definitely not a suicide as we've seen before.' He fell into rhythm of questioning and answering himself, deducing until Sam began to regret asking.

'Okay so you've seen something like this before?' she asked, attempting to stop him from talking.

'Not quite, that was a serial suicide, I have it all recorded on my blog if you're interested.' John answered for Sherlock who was looking about the kitchen.

'Blog?'

'Oh yes, the infamous 'study in pink' ' Sherlock sneered and went off to investigate the cupboards. The name however rang a bell in Sam's mind.

'A study in pink… wait you're _that _Sherlock Holmes?' Sam gasped realisation hitting her as to who she was talking to.

'Well there's no other pompous git named Sherlock Holmes is there.' John commented dryly. 'I'm going to ask Lestrade if the body can be taken to Saint Barts.' He left the kitchen in the same direction.

Sam turned her attention back to the notebook in front of her and glanced up at Sherlock. 'so you're the famous consulting detective that everybody talks about? The one who faked his death?' at that he visibly stiffened and Sam realised what she'd said.

'Oh God I'm sorry that was insensitive of me.' She apologised quickly.

'No it's…it's fine.' He said eventually. An awkward silence fell over the pair but were saved when John re-entered the room.

'Right they're coming to move the body to Barts.'

'Then it's time to go there ourselves.' Sherlock declares and leaves the room. 'Oh and bring the code!' he calls over his shoulder. At that Sam jumps up and follows an exasperated looking John out of the apartment.


End file.
